1. Field of the Invention
The present invention relates to an NC loader for a machine tool, which is particularly suitable for use with an NC lathe, and more specifically to an NC loader for loading small workpieces to be processed onto the NC lathe and unloading small products already processed from the NC lathe automatically in accordance with numerical control.
2. Description of Related Art
Conventionally, an NC loader for loading small workpieces to be processed and unloading products already processed is mounted on an NC lathe in the case where a great quantity of small raw materials are processed (e.g., cut), in particular. In the conventional NC loader, a workpiece loader body movable in the horizontal direction to load a workpiece is disposed over a main spindle, and a hand up-and-down moving cylinder for moving a workpiece loading hand in the vertical direction is mounted on the workpiece loader body. Further, a piston rod for moving the workpiece loading hand up and down is mounted on the hand up-and-down cylinder, and a workpiece loading hand is attached to the lower end of this piston rod. In addition, a workpiece shooter is arranged near an uppermost movement position of the workpiece loading hand. Further, various movement end adjusting stopper members (frontward and reward and upward and downward) are provided for limiting the horizontal movement of the loader body and the vertical movement of the workpiece loading hand, respectively.
On the other hand, a front-and-rear moving cylinder for unloading products is disposed obliquely above the main spindle. Further, a piston rod is mounted on the front-and-rear cylinder, and a product unloading hand is attached to the end of this piston rod. In addition, a product shooter is arranged near an uppermost movement position of the product unloading hand. Further, two movement end adjusting stopper members (forward and reward) are provided for limiting the horizontal movement of the product unloading hand.
In the construction as described above, first the front-and-rear cylinder is actuated to move the product unloading hand to near a chuck attached to the main spindle and then the chuck is opened to release a product into the product unloading hand. After that, immediately after the product unloading hand is moved to the rearward movement position, a lid of the product unloading hand is opened to allow the product to flow along the product shooter.
After the product unloading hand is moved rearward, the front-and-rear cylinder is actuated to move the workpiece loader body to the frontward movement position thereof, and then the hand up-and-down cylinder is actuated to move the workpiece loading hand downward. When the workpiece loading hand has been moved downward, the workpiece loader body is moved backward, so that workpiece is loaded on the chuck. After that, the chuck is fastened to grip the workpiece. Thereafter, the workpiece loader body is moved frontward, and the workpiece loading hand is moved upward. The workpiece loader body is moved rearward again, so that a workpiece is supplied from the workpiece shooter to the workpiece loading hand, and then clamped by the workpiece loading hand. The above-mentioned operation is repeated to load work and unload products.
In the conventional NC loader as described above, however, whenever a workpiece must be replaced with another workpiece for each production schedule, various adjustments are so far required; that is, the frontward and reward and upward and downward stoppers must be readjusted, respectively; the widths of the workpiece shooter and the product shooter must be readjusted, respectively; shooter rails must be replaced with other ones, thus causing problems in that a lot of time and skills are needed for setting-up of the NC loader for the NC lathe, with the result that the NC loader is not suitable for production lines for various models of small quantity.
Further, a sequencer for controlling the NC loader is provided separately for the lathe, it has been necessary to learn the operation of the sequencer and program in order to change the operation sequence.